1. Field of the Invention
The present invention relates to a LAN relaying/switching apparatus, and in particular to a LAN relaying/switching apparatus which accommodates many LAN transmission lines.
In recent years, LAN transmission lines have been made to have a high-speed and large capacity so that it has been required in the LAN relaying/switching apparatus where many LAN transmission lines are concentrated to suppress the spread of faults having occurred in a part of the transmission lines to the other normal transmission lines.
2. Description of the Related Art
FIG. 10 shows an arrangement of a conventional LAN relaying/switching apparatus. This relaying/switching apparatus is composed of terminal portions 20 on the input side and the output side of the apparatus which terminate transmission lines, a switch portion 14 which exchanges data from the terminal portions 20 on the input side and provides the same to the terminal portions 20 on the output side, and queue portions 60a-60c and 60d-60f respectively arranged on the input side and the output side of the switch portion 14 for establishing data forwarding paths.
In this arrangement, the terminal portions 20 on the input side are composed of two terminal portions based on the IEEE802.3 and a single ATM terminal portion so that the terminal portions of different interfaces exist together.
In such a conventional LAN relaying/switching apparatus having physical interface terminal portions based on the IEEE802.3, a jam state {circle around (1)}, caused in the transmission line on the output side for instance, causes an overflow state {circle around (2)} in the output queue portion 60dplaced in front of the terminal portions 20 which terminate the transmission line. The overflow state {circle around (2)} causes an overflow state {circle around (3)}in the queue portions 60a-60c on the input side which transmit the data to the queue portion 60d. 
Being based on the IEEE802.3 in this case, the terminal portions 20 detect the overflow state {circle around (3)} of the queue portions 60a and 60b on the input side, perform a flow control {circle around (4)} a regulated by the IEEE802.3x and the IEEE802.3z, and suppress the data causing the overflow state {circle around (3)}.
On the other hand, the overflow state {circle around (3)} of the queue portion 60c on the input side has no flow control corresponding to the IEEE802.3x and the IEEE802.3z since the terminal portion 20 on the input side is the ATM terminal portion. Therefore, it is impossible to selectively suppress the transmission of the data from the apparatus transmitting the data causing the overflow state {circle around (3)}. For this reason, there has been a problem that cells which have overflowed in the queue portion 60c on the input side are to be discarded as shown by {circle around (5)}.
It is accordingly an object of the present invention to provide a LAN relaying/switching apparatus which accommodates many transmission lines and suppresses the spread of jams caused in a part of the transmission lines to the other normal transmission lines.
In order to achieve the above-mentioned object, a LAN relaying/switching apparatus, according to claim 1, of the present invention comprises; a plurality of terminal portions for inputting data from an external apparatus, a queue portion for performing an input/output management for a switch portion of the data, and a controller for performing a flow control which limits a data transmission for the terminal portions which have inputted the data when a threshold value preset to an output queue of the queue portion is exceeded.
Namely, the data from an external apparatus is inputted to the queue portion through the terminal portions is queued until a path is set up at the switch portion, and is then transferred to the queue portion on the output side through the setup path. In the presence of a jam in the transmission line on the output side, the data is queued at the queue portion on the output side. When the queue (queued number) exceeds the preset threshold value, the controller performs the flow control for limiting the data transfer to the terminal portion which has inputted the data which has exceeded the threshold value.
This operation enables the transmission of the data causing a jam to be limited and prevents the data from overflowing and being lost at the queue portion.
Also, in the present invention according to claim 2, the controller may identify a real terminal portion based on an MAC address included in the data which has exceeded the threshold value.
Namely, the controller identifies the terminal portion from which the data is transmitted based on the MAC address included in the data which has exceeded the threshold value and limits the data transfer to the identified terminal portion.
Also, in the present invention according to claim 3, the controller may identify a real terminal portion based on an IP address included in the data which has exceeded the threshold value.
Furthermore, in the present invention according to claim 4, the controller may identify a real terminal portion based on protocol type information included in the data which has exceeded the threshold value.
Also, a LAN relaying/switching apparatus, according to claim 5, of the present invention may comprise; a plurality of terminal portions for inputting data from an external apparatus, a queue portion for performing an input/output management for a switch portion of the data, and a controller for performing a flow control which limits a specific data flow from the terminal portions where an output queue of the queue portion has exceeded a preset threshold value.
Namely, in the same way as the invention of claim 1, when the queue of the output queue portion has exceeded the threshold value the controller performs the flow control to the data. However, different from the invention of claim 1, this flow control is performed to a specific data flow at the time when the threshold value has been exceeded.
This enables the transmission of the specific data flow causing a jam to be limited and prevents the data from overflowing and being lost at the queue portion on the output side.
Also, in the present invention according to claim 6, the controller may identify the specific data flow based on an MAC address.
Also, in the present invention according to claim 7, the controller may identify the specific data flow based on an IP address.
Also, in the present invention according to claim 8, the controller may identify the specific data flow based on protocol type information.
Also, in the present invention according to claim 9, the controller may identify the specific data flow based on a TCP or UDP port number.
Also, in the present invention according to claim 10, the controller may identify the specific data flow based on a flow label in IPv6.
Moreover, in the present invention according to claim 11, the controller may identify the specific data flow based on one of VPI and VCI information in ATM.
Namely, in the present invention according to any one of claims 6-11, the controller may identify the specific data flow whose transmission is limited based on one of the MAC address, the IP address, the protocol type information, the port number, the flow label, as well as the VPI and VCI information included in the data flow at the time when the threshold value is exceeded.
Also, in the present invention according to claim 12, when any one of a plurality of threshold values which are preset is exceeded, the controller may perform the flow control which limits the specific data flow.
Namely, in the invention of claim 1, a single threshold value is set in the output queue portion, while in the present invention a plurality of threshold values are set. Thus, when the data flow exceeds one of the threshold values, the controller can perform a more minute flow control by limiting a specific data flow stepwise.
Also, a LAN relaying/switching apparatus, according to claim 13, of the present invention comprises; a plurality of terminal portions for inputting data from an external apparatus, a queue portion for performing an input/output management for a switch portion of the data, and a controller for identifying the terminal portions based on address information included in the data at the time when an output queue of the queue portion has exceeded a plurality of threshold values which are preset and for performing a flow control which limits a data transmission based on statistic information of a traffic amount for the identified terminal portions at the time when any one of the threshold values is exceeded.
Namely, in the present invention, the terminal portions which receive the data flow causing a jam are identified to have the flow control performed in the same way as the invention of claim 1. However, different from the invention of claim 1, a plurality of threshold values are set and when one of the threshold values is exceeded, the flow control is performed so as to more efficiently use the band capacity of the transmission line accommodated by the identified terminal portions based on the statistic information of the traffic amount.
This enables the controller to perform a more minute flow control and to efficiently use the transmission line.
Also, a LAN relaying/switching apparatus, according to claim 14, of the present invention comprises; a plurality of terminal portions including an ATM terminal portion for inputting data from an external apparatus, a queue portion for performing an input/output management for a switch portion of the data, and a controller for transmitting an RM (Resource Management) cell so as to limit the data flow from the ATM terminal portion when a data flow at the time when an output queue of the queue portion has exceeded a preset threshold value is a specific data flow from the ATM terminal portion.
This invention corresponds to the LAN relaying/switching apparatus where the terminal portions inputting the specific data flow are ATM terminal portions, in the invention of claim 5.
Namely, the controller transmits the RM cell which limits the band of the specific data flow from the ATM terminal portions to the apparatus transmitting the date flow causing a jam, thereby suppressing the data flow amount.
This enables the controller to perform the flow control to the data flow from the ATM terminal portions and to suppress the occurrence of a cell discard.
Also, in the LAN relaying/switching apparatus, according to claim 15, of the present invention, when the queue of the queue portion which transmits the specific data flow has exceeded a preset threshold value and the specific data flow is a data flow from the terminal portions based on IEEE802.3, the controller which has received the RM cell may perform a flow control so as to temporarily pause the data flow.
This invention relates to the LAN relaying/switching apparatus which has received the RM cell from the LAN relaying/switching apparatus of the invention according to claim 14.
Namely, when the terminal portions inputting the specific data flow designated by the RM cell are based on the IEEE802.3, the controller which has received the RM cell performs the flow control for temporarily pausing the transmission of the specific data flow from the terminal portions.
This enables the controller to perform the flow control to the data flow from the terminal portions based on the IEEE802.3 causing a jam of the transmission line connected to the ATM terminal portions.
Furthermore, in the LAN relaying/switching apparatus, according to claim 16, of the present invention, when the queue of the queue portion which transmits the specific data flow has exceeded a preset threshold value, the controller which has received the RM cell may perform a flow control to set a CLP (Cell Loss Priority) bit of cell in the specific data flow to non-priority.
Namely, when the queue of the queue portion transmitting the specific data flow has exceeded a predetermined threshold value, the controller which has received the RM cell from the LAN relaying/switching apparatus of the invention according to claim 14 sets the CLP bit of the cell in the specific data flow to non-priority. Then the controller transmits the CLP bit to the LAN relaying/switching apparatus from which the RM cell is transmitted.
If there is a possibility that the cell where the CLP bit is set to non-priority causes a jam, the LAN relaying/switching apparatus will discard the cell.
Also, in the LAN relaying/switching apparatus, according to claim 17, of the present invention, when a plurality of threshold values exist and the queue has exceeded any one of the threshold values, the controller may set the CLP bit to non-priority corresponding to the threshold value.
Namely, in the above-mentioned invention of claim 16, a plurality of threshold values are set in the queue portion. When the specific data flow has exceeded one of the threshold values, the controller sets the CLP bit of the cell in the specific data flow to non-priority at a stage corresponding to the threshold value.
This enables more cells based on the CLP bit to be discarded compared with the flow control in the invention of claim 16, resulting in a more minute control.